package com.unhz.generator.utils;


  import java.util.concurrent.Executors;
  import java.util.concurrent.ScheduledExecutorService;
  import java.util.concurrent.TimeUnit;
  import org.eclipse.paho.client.mqttv3.MqttClient;
  import org.eclipse.paho.client.mqttv3.MqttConnectOptions;
  import org.eclipse.paho.client.mqttv3.MqttException;
  import org.eclipse.paho.client.mqttv3.MqttSecurityException;
  import org.eclipse.paho.client.mqttv3.MqttTopic;
  import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;
    public class Client {
   public static final String HOST = "tcp://0.0.0.0:61613";
     public static final String TOPIC = "toclient/124";
     private static final String clientid = "client124";
     private MqttClient client;
     private MqttConnectOptions options;
     private String userName = "admin";
     private String passWord = "password";

        private ScheduledExecutorService scheduler;

        private void start() {
                    try {
                            // host为主机名，clientid即连接MQTT的客户端ID，一般以唯一标识符表示，MemoryPersistence设置clientid的保存形式，默认为以内存保存
                            client = new MqttClient(HOST, clientid, new MemoryPersistence());
                            // MQTT的连接设置
                            options = new MqttConnectOptions();
                            // 设置是否清空session,这里如果设置为false表示服务器会保留客户端的连接记录，这里设置为true表示每次连接到服务器都以新的身份连接
                            options.setCleanSession(true);
                            // 设置连接的用户名
                            options.setUserName(userName);
                            // 设置连接的密码
                            options.setPassword(passWord.toCharArray());
                            // 设置超时时间 单位为秒
                            options.setConnectionTimeout(10);
                            // 设置会话心跳时间 单位为秒 服务器会每隔1.5*20秒的时间向客户端发送个消息判断客户端是否在线，但这个方法并没有重连的机制
                            options.setKeepAliveInterval(20);
                             // 设置回调
                            client.setCallback(new PushCallback());
                             MqttTopic topic = client.getTopic(TOPIC);
                             //setWill方法，如果项目中需要知道客户端是否掉线可以调用该方法。设置最终端口的通知消息
                             options.setWill(topic, "close".getBytes(), 2, true);

                             client.connect(options);
                             //订阅消息
                             int[] Qos  = {1};
                             String[] topic1 = {TOPIC};
                             client.subscribe(topic1, Qos);

                         } catch (Exception e) {
                             e.printStackTrace();
                         }
               }
     public static void main(String[] args) throws MqttException {
                     Client client = new Client();
                     client.start();
                 }
 }

